1. Field of the Invention
The present invention relates to the field of in vivo sensors and, in particular, to in vivo sensors that are implanted in non-vascular areas of the body.
2. Description of Related Art
Traditional methods of physiological parameter sensing typically rely on vascular placement of a physiological parameter sensor. Such placement permits a sensing element such as, for example, a biomolecule, to make direct contact with the blood, providing sensing capabilities of blood components. Such sensing capabilities have greatly facilitated analysis, diagnosis and treatment of many debilitating diseases and medical conditions.
However, vascular placement of a physiological parameter sensor may suffer from several disadvantages. A physiological parameter sensor is not inserted into a vein without great difficulty and painstaking effort by an attending physician. Moreover, a physiological parameter sensor is not adjusted within or extracted from a vein without similar difficulty and effort.
Furthermore, vascular placement of a physiological parameter sensor subjects the sensor to a constant fluid environment. Such an environment may have several detrimental effects on the sensor. Due to constant fluidic contact, the sensor may suffer from decreased sensitivity, stability and effective life. Should a characteristic of the sensor be diminished to an extent rendering the sensor ineffective, the sensor must be removed and replaced, introducing the difficulties for both patient and physician associated with such removal and replacement. To complicate matters, every time a physiological parameter sensor is removed and replaced, it must be disconnected and reconnected to an implant unit utilizing the sensor output.
In an effort to assuage some of the disadvantages associated with vascular implantation of physiological parameter sensors, integrated sensor/implant unit systems have been developed. Such systems may be placed in or near a body cavity and may provide non-vascular sensing of physiological parameters. However, the incision required for such sensor/implant unit systems is relatively large and the trauma in the area of implantation can be significant. Such trauma generally prevents sensing of physiological parameters. Because such trauma may not subside for several weeks or a month or even longer, pre-implantation analysis methods used by the patient must continue. Without continuation of preimplantation analysis methods, a patient may go undiagnosed and untreated for many weeks, possibly even a month or longer. Such delay in treatment and diagnosis could be harmful or even fatal for patients who need daily diagnosis and treatment.